1. Field of the Invention
This invention relates to a synchronizing system for connecting two rotary bodies arranged in a manner spaced from each other and at the same time relatively rotatable about an identical axis while synchronizing the two rotary bodies with each other, so as to transmit torque between the two rotary bodies, and a transmission torque control device for controlling the torque transmitted between the two rotary bodies by the synchronizing system.
2. Description of the Prior Art
Conventionally, a synchronizing system of this kind has been proposed e.g. in Japanese Laid-Open Patent Publication (Kohyo) No. 11-501104, which is applied to a transmission for an automotive vehicle, and executes a synchronizing operation for synchronizing a transmission shaft and a transmission gear coaxial with the transmission shaft when they are relatively rotating. This synchronizing system includes a synchronizing body rotating together with the transmission shaft, and a sleeve which rotates together with the synchronizing body and is capable of sliding along the axis with respect to the synchronizing body. Further, the sleeve is comprised of two inner and outer disc holders, a multiple disc clutch which is disposed between the two disc holders and formed by a lot of friction discs connected to the outer disc holder and a lot of friction discs connected to the inner disc holder, which are arranged alternately in the axial direction to have a comb teeth-like shape as a whole, and a disc spring for always urging the above friction discs in the axial direction. During the synchronizing operation, when the sleeve is pressed toward the transmission gear by a gear switching device to cause the outer disc holder of the sleeve to mesh with the transmission gear, and at the same time the inner disc holder is urged toward the transmission gear by the gear switching device to urge the lot of friction discs toward the transmission gear via the disc spring, whereby the large number of friction discs are brought into abutment with each other. The abutment of the friction discs generates frictional forces, whereby synchronization of the transmission gear and the transmission shaft is started, and torque is transmitted between the transmission gear and the transmission shaft.
According to the above conventional synchronizing system, the synchronizing operation for synchronizing the transmission gear and the transmission shaft is carried out by the urging force of the disc spring, so that the torque transmitted between the transmission gear and the transmission shaft during the synchronizing operation is limited to a value equal to or smaller than a limit value determined by the urging force of the disc spring. As a result, the conventional synchronizing system suffers from the problem that when an input torque is larger than the limit value, the torque can be transmitted only in a range within the limit value.
It is an object of the invention to provide a synchronizing system which synchronizes two relatively rotating rotary bodies with each other by frictional forces generated between friction discs, such that a larger torque can be transmitted between the rotary bodies as an input torque becomes larger, and a transmission torque control device for the synchronizing system.
To attain the above object, according to a first aspect of the invention, there is provided a synchronizing system for connecting a first rotary body and a second rotary body arranged in a manner spaced from each other and at the same time relatively rotatable about an identical axis, while synchronizing the first rotary body and the second rotary body with each other so as to transmit torque between the first rotary body and the second rotary body.
The synchronizing system according to the first aspect of the invention is characterized by comprising:
an engagement member which is arranged between the first rotary body and the second rotary body in a manner such that the engagement member is capable of moving along the axis and rotating about the axis relatively with respect to each of the first rotary body and the second rotary body;
at least one first friction disc rotating together with the first rotary body;
at least one second friction disc each arranged in a manner opposed to and spaced from the at least one first friction disc, the at least one second friction disc rotating together with the engagement member, and being brought into surface contact with the at least one first friction disc when the engagement member is urged toward the first rotary body, thereby synchronizing the engagement member and the first rotary body with each other;
a movable member which rotates together with the second rotary body and is capable of moving along the axis with respect to the second rotary body such that the movable member can move to a disconnected position in which the movable member is spaced from the engagement member, a synchronizing position in which the movable member is capable of abutting against the engagement member from an opposite side to the first rotary body, and a connected position in which the movable member is engaged with the first rotary body; and
a synchronizing member which, when the movable member moves from the disconnected position to the synchronizing position, is driven by the movable member to thereby urge the engagement member toward the first rotary body, whereby the synchronizing member starts to synchronize the first rotary body and the second rotary body via the at least one first friction disc and the at least one second friction disc and causes the engagement member to abut against the movable member located in the synchronizing position.
According to this synchronizing system, the first rotary body and the second rotary body are connected or linked to each other in a state in which the movable member is in a connected position in which the same is engaged with the first rotary body, and disconnected or released from each other in a state in which the movable member is in a disconnected position in which the same is spaced from the engagement member. Further, when the movable member moves from the disconnected position to the synchronizing position, the synchronizing member is driven by the movable member to thereby urge the engagement member toward the first rotary body, whereby the first rotary body and the second rotary body start to be synchronized via the at least one first friction disc and the at least one second friction disc, and the engagement member is brought into abutment with the movable member located in the synchronizing position to be urged by the movable member. In this state, the first rotary body and the second rotary body are mechanically connected to each other via the movable member, the engagement member, the at least one first friction disc and the at least one second friction disc. As a result, the torque transmitted between the first rotary body and the second rotary body is increased since as the urging force of the movable member applied to the engagement member is increased, frictional forces generated between the at least one first friction disc and the at least one second friction disc are increased. Therefore, differently from the conventional synchronizing system in which torque to be transmitted is limited to a value within a limit value determined by the urging force of a disc spring, the urging force of the movable member applied to the engagement member is made larger during the synchronizing operation for synchronizing the first rotary body with the second rotary body even when the input torque is large, whereby a larger torque dependent on the increased urging force can be transmitted between the first and second rotary bodies. Further, through the control of the urging force of the movable member applied to the engagement member, it becomes possible to control the torque transmitted between the first and second rotary bodies.
Preferably, the second rotary body comprises a drive shaft, and a hub rotating together with the drive shaft.
More preferably, the first rotary body has first splines formed in an outer peripheral surface thereof, the engagement member having second splines formed in an outer peripheral surface thereof, the hub having third splines formed in an outer peripheral surface thereof, the movable member having fourth splines formed in an inner peripheral surface thereof for being in engagement with the third splines of the hub, and the fourth splines of the movable member are in abutment with the second splines of the engagement member when the movable member is in the synchronizing position, and in engagement with the second splines of the engagement member and the first splines of the first rotary body when the movable member is the connected position.
Further preferably, the first rotary body has a large-diameter portion and a small-diameter portion, the first splines of the first rotary body being formed in an outer peripheral surface of the large-diameter portion, the small-diameter portion having fifth splines formed in an outer peripheral surface thereof, the at least one first friction disc each having sixth splines formed in an inner peripheral surface thereof, and the fifth splines of the small-diameter portion of the first rotary disc are in engagement with the sixth splines of the at least one first friction disc.
Still more preferably, the engagement member has seventh splines formed in an inner peripheral surface thereof, the at least one second friction disc each having eighth splines formed in an outer peripheral surface thereof, and the seventh splines of the engagement member are in engagement with the eighth splines of the at least one second friction disc.
To attain the above object, according to a second aspect of the invention, there is provided a transmission torque control device for a synchronizing system for connecting a first rotary body and a second rotary body arranged in a manner spaced from each other and at the same time relatively rotatable about an identical axis, while synchronizing the first rotary body and the second rotary body with each other so as to transmit torque between the first rotary body and the second rotary body, the synchronizing system including an engagement member which is arranged between the first rotary body and the second rotary body in a manner such that the engagement member is capable of moving along the axis and rotating about the axis relatively with respect to each of the first rotary body and the second rotary body, at least one first friction disc rotating together with the first rotary body, at least one second friction disc each arranged in a manner opposed to and spaced from the at least one first friction disc, the at least one second friction disc rotating together with the engagement member, and being brought into surface contact with the at least one first friction disc when the engagement member is urged toward the first rotary body, thereby synchronizing the engagement member and the first rotary body with each other, a movable member which rotates together with the second rotary body and is capable of moving along the axis with respect to the second rotary body such that the movable member can move to a disconnected position in which the movable member is spaced from the engagement member, a synchronizing position in which the movable member is capable of abutting against the engagement member from an opposite side to the first rotary body, and a connected position in which the movable member is engaged with the first rotary body, and a synchronizing member which, when the movable member moves from the disconnected position to the synchronizing position, is driven by the movable member to thereby urge the engagement member toward the first rotary body, whereby the synchronizing member starts to synchronize the first rotary body and the second rotary body via the at least one first friction disc and the at least one second friction disc and causes the engagement member to abut against the movable member located in the synchronizing position,
wherein the transmission torque control device controls the torque transmitted between the first rotary body and the second rotary body.
The transmission torque control device according to the second aspect of the invention is characterized by comprising:
driving means for driving the movable member along the axis;
torque detection means for detecting torque of at least one of the first rotary body and the second rotary body; and
driving force setting means for setting a driving force of the driving means applied when the movable member is in abutment with the engagement member, based on the detected torque.
According to this transmission torque control device, the driving force of the movable member driven by the driving means is set based on the detected torque of at least one of the first rotary body and the second rotary body, and the movable member urges the engagement member with an urging force corresponding to the driving force set or determined. As described hereinabove, in this synchronizing system, the torque transmitted between the first rotary body and the second rotary body during a synchronizing operation depends on the urging force of the movable member applied to the engagement member. Hence, according to the transmission torque control device configured as above, the transmission torque transmitted during the synchronizing operation can be properly controlled depending on the input torque and the difference between the input torque and the output torque.
The above and other objects, features, and advantages of the invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.